Servlet中实现用servletContext对象统计网站在线人数

来源：互联网发布：软件开发项目预算表编辑：程序博客网时间：2024/06/05 17:23

1：servletContext

package com.study;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class IndexServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
ServletContext ctx=this.getServletContext();
synchronized(this)
{
Integer counter=(Integer)ctx.getAttribute("userNumber");
int temp=0;
if(counter==null)
counter=new Integer(1);
else
{
temp=counter.intValue()+1;
counter=new Integer(temp);
}
ctx.setAttribute("userNumber", temp);
}
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML>");
out.println("<html>");
out.println("<head><title>login Servlet</title></head>");
out.println("<body>");
out.print("这是第一页<br/>");
out.print("<a href='UserNumberServlet'>人数统计</a>");
out.println("</body>");
out.println("</html>");
out.flush();
out.close();

}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

}

}

2;统计在线人数

package com.study;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class UserNumberServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
response.setContentType("text/html");
PrintWriter out = response.getWriter();
ServletContext ctx=this.getServletContext();
Integer counter=(Integer)ctx.getAttribute("userNumber");
out.println("<!DOCTYPE HTML>");
out.println("<html>");
out.println("<head><title>统计在线人数</title></head>");
out.println("<body>");
if(counter==null)
out.print("恭喜您是第一个访问本网站的用户!");
else
out.print("已经有"+counter+"人在访问本网站");
out.println("</body>");
out.println("</html>");
out.flush();
out.close();

}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

}

}

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